Does fitness proportionate selection select multiple individuals?
Yes, you select the same individual multiple times, according to the distribution of fitness values. Typically, you have at least as many offspring as parents, so if you didn't replace parents in the pool to be potentially selected again, you'd just have every parent being selected once, which defeats the purpose of selection. You want fitter parents to be selected more often so that you drive the average fitness higher across generations.

That said, there are no iron clad rules. There are algorithms that create selection pressure in other ways, and you can do whatever works for you. But in the canonical version of a GA, you do selection with replacement. Though, many people find other selection schemes like tournament selection perform better across a pretty wide range of problems than roulette wheel anyway.